We propose to investigate ethnic differences in biological pain regulatory mechanisms and psychosocial factors. Specifically, we will examine ethnic differences in temporal summation of heat pain, which may be indicative of central sensitization in pain pathways, the relationships involving stress-responsive biological measures and pain sensitivity, as well as psychosocial factors known to predict pain in African Americans. A sample of 88 medically healthy individuals (50% African American; 50% Women) will be recruited to participate. Individuals will report to the lab for a testing session, during which the participants will complete psychosocial measures to assess stress, coping, and emotion expression. The subjects will undergo testing for pain tolerance to hand cold pressor pain and tourniquet ischemic pain, and the temporal summation procedure involving delivery of heat pulses at 53[unreadable]C will be administered.. Blood pressure and plasma norepinephrine, cortisol, and beta-endorphin levels will then be measured at baseline and during a standardized mental stressor battery. The results of this study are expected to provide insight into biobehavioral and psychosocial factors that may contribute to ethnic disparities in clinical pain.